Mensaje de S.E la Presidenta de la República con el que inicia un proyecto de ley que modifica el Código Procesal Penal y otros cuerpos legales en lo relativo al proce-

Different measuring tools and devices have been used during tests, which include:

The three phase measurement unit: This measuring device measures the instantaneous three phase currents and voltages based on Hall Effect current and voltage transducers. The voltage transducer is the LEM LV 25-P and the current transducer is the ABB

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EL55P2. The photographic and the schematic diagram of the three phase measuring device are shown in Figure 4.4 and the specifications of the voltage and current transducers are presented in Table 10 and 11 respectively.

Accelerometers: the vibration of induction motor, GB1 and GB2 are measured using an ICP-type Accelerometer. The accelerometers are placed horizontally in parallel with shafts centrelines of the machines, as shown in Figure 4.1.

Figure 4.4 Three phase electrical signals measurement device

Table 10. Specifications of the voltage transducer

Brand and Type LEM Voltage Transducer LV 25-Pt

Primary nominal voltage (Vpn)rms 10 : 500 V

Primary nominal current (Ipn)rms 10 mA

Primary current, measuring range 0 : ±14 mA

Secondary nominal current (Isn)rms 25 mA

Supply voltage (±5%) ± (12:15) V

Current consumption 10(@±15V) + Is mA

Overall accuracy ±0.9% @ (Ipn , 25oC and ±15V)

Linearity error <0.2%

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Table 11. Specifications of the current transducer

Brand ABB

Type Current Transducer EL55P2

Technology Hall Effect

Primary nominal current (Ipn)rms 50 A

Supply voltage (Va) ±(11:15.7) V

Measuring range @ Va 0 : ±80 A

Secondary nominal current (Isn)

rms 25 mA Thermal drift/ Isn 2*10-4 /oC Bandwidth (-1 dB) 0:200 kHz Accuracy ±0.5% @ (Ipn , 0:70 o_{C and} ±15V)

Linearity Better than 10-3

Response time <0.1 s

No load current consumption 1 6 (@±15V Va) mA

Thermocouples: the temperature of the oil inside each gearbox is measured using K type thermocouples. The signal from the thermocouple is sent to the temperature processing unit for filtering and magnification.

Speed encoder: An optical speed encoder is attached to the AC motor to measure the system speed. The encoder is the RS32-O/100ER, manufactured by Hengstle. It has two outputs, one producing 100 pulses per revolution and the other 1 pulse per revolution. The encoder is connected to the data acquisition system directly and not utilised in the control system. Figure 4.1 illustrates how the encoder fitted on the rear of the AC motor.

Dial indicator: this tool is used for aligning the rig. It is the EDI-125 and has an accuracy of ±0.005mm, measurement range: 12.7 mm with 0.001mm resolution. The dial indicator is fitted on a magnetic base that allows it to be fitted on the shaft for adjusting the alignment. Figure 4.5 depicts this indicator during an alignment process.

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Figure 4.5 Digital dial indicator for shaft alignment (author)

Pre-cut standard shims: sstainless steel standard pre-cut shims are used for adjusting the alignment of the rig and also for seeding the misalignment faults. Different sizes are used to obtain the best possible alignment. To misalign the rig these shims are placed under the item when needed. Figure 4.1 illustrates how these shims are placed under the GB1.

Volumetric measuring tools: a beaker and pipette for measuring the quantities of oil and water respectively.

Test Rig Operation

The schematic of the rig is shown in Figure 4.6. The operator enters the required test profile via the touch screen interface. The rig PLC obtains this profile which includes number of cycles, speed reference, load reference and time duration for each cycle. Up to 12 cycles can be programmed. When the user starts the rig, the PLC sends the reference values and start commands to both the AC VSD and the DC VSD.

The AC VSD runs the AC motor at the required speed, without feedback speed encoder, benefits from the built in PI controllers and the Model Reference Adaptive System (MRAS). The DC drive feeds the DC load generator with the proper supply based on the load settings from the PLC. The DC drive regulates the armature and field currents of the DC load generator to adjust the load. This provides the ability to study the

system’s behaviour under different speed and load conditions as well as the transient

process between different conditions.

When the AC motor rotates, both gear boxes rotate, the first gearbox reduces the speed, while the second gearbox increases it again to the original speed and rotates the DC motor with the same speed of the AC motor. The PLC obtains feedback signals from

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both AC VSD and DC speed driver, including: AC current, load feedback (DC armature current), and speed feedback, and shows them on the rig screen.

Figure 4.6 Schematic of the test rig

Faults Simulated

Four different faults were studied, i.e. shaft misalignment, water in oil contamination, gearbox oil viscosity changes and gearbox lubricating shortage referred to as oil level tests. The studied faults represent some of the most common faults that occur in mechanical transmission systems. Additionally, the detection of these faults using power supply parameters within a sensorless controlled transmission system is not yet well discovered. Tests performed are to examine the performance of the fault detection scheme and to investigate the diagnosis capabilities of the power supply parameters together with control data, particularly in the case of a mechanical transmission system driven with a sensorless variable speed drive.

4.4.1 Shaft Misalignment

The misalignment is seeded into the rig by placing standard pre-cut stainless steel shims under the GB1. Four different degrees of parallel shaft misalignments are simulated;

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i.e. 0.3 mm, 0.5 mm, 0.7mm, and 1.00 mm successively. The permissible misalignment limit for the couplings is 0.4 mm.

The rig is firstly aligned at the lowest possible misalignment using the dial indicator (this was at 0.04±0.01 mm). A cycle of 5 different load settings was applied, 0%, 25%, 50%, 75% and 100% of the full load. Each load is applied for a period of two minutes. The AC motor speed is set at its full speed during the tests. A set of 10 seconds of dynamic data is collected for each load, while the data from the VSD is logged for the entire cycle.